Biology: Use and abuse of drugs

Drugs

Drugs are substances that change chemical reactions in the body. 

Medical drugs relieve disease and illness and extensively tested. 

Recreational drugs are taken by people because they like the effect they have on their body and can often be addictive. 

New medical drugs have to be tested to ensure they work and are safe before they can be prescribed. There are three main stages of testing:

• The drugs are tested using computer models and human cells grown in a laboratory. Many substances fail this part because they damage cells or don't seem to work.
• Drugs that pass this stage are then tested on animals. In the UK, new medicines have to undergo these tests but it's illegal to test tobacco or cosmetic products on animals. A typical test involves giving a known amount of the substance to the animals then monitoring them carefully for any side effects.
• Drugs that pass animal test are used in clinical trials. They are tested on healthy volunteers to check that they're safe. Very low doses are given at first to check that they are safe then further clinical trials are run to find the optimum dose. 

Clinical trials are not without risk and sometimes severe and unexpected side effects happen. Most substances don't pass all the tests so drug development is expensive and takes a long time. 

It's important to be sure that the drug does actually work and that people aren't just feeling better because they expect to (placebo effect). Double blind trials are run to minimise the placebo effect. Some patients are given the drug and others are given a placebo. The doctors and patients do not know who is given…